21137345640 has 96 divisors (see below), whose sum is σ = 69637506120. Its totient is φ = 5559404544.

The previous prime is 21137345633. The next prime is 21137345659. The reversal of 21137345640 is 4654373112.

21137345640 is a `hidden beast` number, since 2 + 1 + 1 + 3 + 7 + 3 + 4 + 5 + 640 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 20720450916 + 416894724 = 143946^2 + 20418^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 21137345595 and 21137345604.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 375877 + ... + 428436.

Almost surely, 2^21137345640 is an apocalyptic number.

21137345640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21137345640 is an abundant number, since it is smaller than the sum of its proper divisors (48500160480).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21137345640 is a wasteful number, since it uses less digits than its factorization.

21137345640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 804403 (or 804396 counting only the distinct ones).

The product of its (nonzero) digits is 60480, while the sum is 36.

The spelling of 21137345640 in words is "twenty-one billion, one hundred thirty-seven million, three hundred forty-five thousand, six hundred forty".